Having 12 points isn't required, but does help distinguish you from other chefs. I get by ok with only ten points, myself.
But, if you want to go that route, here's what you need:
1) You get one additional point for every +10 bonus in tapes, so you'll need at least +20 worth of tapes to get 12 points.
2) Right now, putting a tape into a piece of clothing with the same bonus (whether it's the crafter's apron or had prior tapes) does not stack bonuses. You end up with only the higher of the two. So if you put a +4 tape into a crafter's apron (with its built-in +5), it ends up only as +5. If you put a +6 tape into the apron it becomes +6 (not +11).
3) Because of that, and you only have a limited number of pieces of clothing you can wear, just accumulating a bunch of +1 tapes won't really be enough. IIRC, the pieces you can wear simultaneously are: shoes, pants, belt, shirt, jacket (apron uses this slot), gloves, bandolier, and hat. A bandolier uses the same clothing slot as a backpack (which cannot take tapes), so you'd have to give up inventory space for that. This is only eight slots for most races, seven for Mon Cal (can't wear gloves), six for trandos (since they can't wear shoes or gloves), and I'm not sure what is available for wookiees.
4) Not all clothing has sockets, especially with a tailor fix recently that reduced the number pretty drastically. A Master tailor is almost guaranteed at least one socket, but four-socket clothing has gotten much more rare. Socketed clothing will be a different color, and will say "Free sockets: ##" in the description.
5) Prices for tapes are very high, but do vary by server. Most seem to go for 100k per point for less than +5, and up to a million per point for bonuses larger than +5. Since crafter's aprons give you +5 and tend to go for 200k to 500k, that is definitely a cost-effective purchase. Tape sales are usually up on the trade forum for your server, you'll rarely find any for sale on vendors (and those are likely only +1 or +2). You can also try looting them yourself if you've got the combat skills, but I don't know if there's any "more likely" mobs that drop them. In general, higher-level mobs drop better loot, so if you can take on a Nightsister...
#2 has pretty much been confirmed as a bug, but no real word on when it's going to be fixed. There are also tapes with multiple bonuses (such as "+4 Food Experimentation, +2 Dodge"), those seem to only give you one of the bonuses, not both. A bunch of theories are out there about which gets picked (highest bonus, first listed, first alphabetically, etc), but I don't know how well they hold up.
And if your question is blatently not in the FAQ, I hope you don't think you have to point out that you checked it. We don't come off as that hostile, do we?

Kriles Ch'artoff , Chilastra server
Master Chef (retired)
Currently doing....stuff